Tunnel

Ventilation Fans

Overview

The need for tunnel ventilation is critical for the life and safety of any person utilizing the metro, rail or road tunnels throughout the world. Typically the equipment is used for smoke extraction or control for the time it takes people to evacuate the tunnel under emergency conditions. They are also utilized to control exhaust fumes and to provide standard ventilation when required.

There are three basic types of control that can be utilized: Portal to Portal, Shaft to Shaft and Portal to Shaft. These are used independently or in conjunction with each other. Fans utilized are both Axial, reversible and unidirectional as well as centrifugal.

Portal to Portal

The concept of portal to portal is typically completed with the use of Jet Fans. These specially designed units are inclusive of an attenuator on either end and direct the air from one portal to the other by inducing the air to move. These units are rated on the thrust that they can impart to the surrounding air in the tunnel. This air movement is sustained by the thrust being energized repeatedly down the length of the tunnel by various banks of Jetfans. The principal objective is to have the air contaminated with smoke move in the opposite direction of the evacuation route. This will allow the people to exit with fresh air blowing in their face.

Shaft to Shaft

The concept of shaft to shaft is a push pull system. The air is forced in the direction required by either a single unit or a station of fans on either side of the fire event. It is standard for the air to be injected from one station and extracted at the other. Thus the equipment for utilized for this type of arrangement must be reversible. The principal objective is to have the air contaminated with smoke move in the opposite direction of the evacuation route. This will allow the people to exit with fresh air blowing in their face.

Portal to Shaft

The concept of portal to shaft is a combination of portal to portal to shaft to shaft. The air is forced into the tunnel and then extracted out of the portal via JetFans. Or depending on the location of the fire event the airflow may be reversed. Hence, the equipment for utilized for this type of arrangement must be reversible. The principal objective is to have the air contaminated with smoke move in the opposite direction of the evacuation route. This will allow the people to exit with fresh air blowing in their face.